If you want to know how to sew DIY bag or purse straps then we have a wonderful free tutorial here from a fabulous bag designer.
Over the years she has written many tutorials for tote bags and as she says there are pretty much just 3 different kinds of handles or straps that she uses:
Straps that get sewn onto the sides of a bag
Straps that are sewn into a seam
Clip-on straps or handles.
This a tutorial for the third kind, the clip-on strap or handle.
In the photo above there are 3 straps shown, the first is 1/2” wide, the next one down is 3/4” wide, and the bottom strap is 1” wide. All three widths are great for a cross-body bag and you’ll want to pick which one would look best with your particular bag. The larger and heavier the bag, the wider the strap you would want to add, to be able to carry it comfortably.
Obviously, the strap will have to clip on to a D-ring or some other piece of hardware fitted to the body of the bag. The width of your strap does not have to match the width of your tab that holds the hardware. Just make sure that your clip and the hardware it will clip to are compatible before you get started.
This can also be used to create a removable strap. If you have a bag that you normally carry by hand, you can give yourself the option to convert it into a shoulder bag or cross body bag from time to time by sewing a strap like this, and only use it when needed.
We love adding the option of a narrow shoulder strap to an evening clutch bag. Then if you have wine in one hand, a plate of food from the buffet in the other hand, you can clip on a narrow strap and hang your clutch bag from your shoulder.